1. Field of the Invention
The present invention relates to a movable contact body mainly used for operation of various electronic apparatuses, and a switch using the same.
2. Background Art
Recently, in various electronic apparatuses, portable terminal equipment such as cell phones in particular, apparatuses with operational sections illuminated by light emitted from light emitting diodes or EL (electro-luminescence) elements so that push-buttons and display sheets or the like can be easily distinguished and manipulated even in the dark are increasing, and movable contact bodies or switches used in these apparatuses are also required to be able to inexpensively perform such lighting for illumination.
A conventional movable contact body and switch disclosed in Unexamined Japanese Patent Publication 2007-141269 is described with reference to FIG. 7. The drawing is dimensionally enlarged in the direction of thickness for making it easier to see the configuration. FIG. 7 is a sectional view of a conventional switch.
In FIG. 7, lower base sheet 1 is a film having optical transparency. Lower electrode 2 is a band formed from indium tin oxide or the like, and it is optically transmissive. A plurality of lower electrodes 2 are arranged at predetermined intervals on the upper surface of lower base sheet 1.
Also, upper base sheet 3 is a film having optical transparency. Upper electrode 4 is a band formed from indium tin oxide, and it is optically transmissive. A plurality of upper electrodes 4 are arranged at predetermined intervals on the upper surface of upper base sheet 3 in a direction perpendicular to lower electrodes 2.
Further, protective sheet 5 is a film having optical transparency. Upper base sheet 3 with upper electrodes 4 arranged thereon is laminated on the upper surface of lower base sheet 1 with lower electrodes 2 arranged thereon. Also, protective sheet 5 is laminated on the upper surface of upper base sheet 3 with upper electrodes 4 arranged thereon. Further, these are bonded to each other by adhesive (not shown) or the like to configure touch panel 6.
A specified portion of the periphery of cover sheet 7 is attached to the underside of touch panel 6 by using adhesive (not shown). Further, a plurality of movable contacts 8 are attached to the underside of cover sheet 7, thereby configuring movable contact body 9. Cover sheet 7 is a film. Each movable contact 8 is nearly a dome which is formed from a conductive metal sheet.
Also, on the upper surface of wiring board 10 formed with a plurality of wiring patterns (not shown) on the upper and lower surfaces thereof are disposed a plurality of fixed contacts 11 formed of nearly circular central fixed contacts 11A and nearly horseshoe-shaped or nearly ring-shaped outer fixed contacts 11B disposed there around.
Further, movable contact body 9 is attached to the upper surface of wiring board 10 in such manner that the outer periphery of each movable contact 8 is placed on outer fixed contact 11B. Also, movable contact body 9 is attached to the upper surface of wiring board 10 in such manner that the underside center of movable contact 8 is opposed to central fixed contact 11A at predetermined intervals.
A plurality of light emitting elements 12 such as light emitting diodes are mounted on the upper surface of wiring board 10, and these are arranged between a plurality of movable contacts 8 with their light emitting surfaces faced upward.
Also, shielding portion 13A is formed by printing or the like on the underside of display sheet 13 which is a film having optical transparency. Specified parts of shielding portion 13A are punched out into shapes of letters and marks or the like to form a plurality of display portions 13B. Display portions 13B are arranged above movable contact 8, thereby configuring a switch.
A switch having such a configuration is mounted on the operation surface of an electronic apparatus. Lower electrodes 2 and upper electrodes 4 of touch panel 6, central fixed contacts 11A and outer fixed contacts 11B, and light emitting elements 12 are connected to an electronic circuit (not shown) of the electronic apparatus via a wiring pattern or lead wire (not shown).
In the above configuration, with a voltage applied from the electronic circuit to a plurality of lower electrodes 2 and upper electrodes 4 in order, when the upper surface of display sheet 13 is lightly touched with the finger for executing touch operation, then a part of the charge of touch panel 6 travels to the finger. Accordingly, the capacitance change takes place between lower electrode 2 and upper electrode 4 under the manipulated portion. As a result, which portion of display sheet 13 was subjected to touch operation is detected by the electronic circuit.
Also, when specified display portion 13B of display sheet 13 is pressed downward, display sheet 13 and touch panel 6 flex and it causes the central portion of the nearly dome-like shape of movable contact 8 to be pressed. In this way, when a specified pressing force is applied, movable contact 8 is resiliently reversed downward while providing a click feeling. In this case, the underside center surface of movable contact 8 comes in contact with central fixed contact 11A, then central fixed contact 11A and outer fixed contact 11B are electrically connected to each other via movable contact 8. As a result, display portion 13B then pressed is detected by the electronic circuit.
When the pressing force to display sheet 13 is released, movable contact 8 is resiliently reversed upward due to the resiliently restoring force, and the underside center of movable contact 8 moves apart from central fixed contact 11A. In this way, central fixed contact 11A and outer fixed contact 11B are electrically disconnected from each other.
Various functions of an apparatus are switched in accordance with the touch operation and pressing operation. When power is supplied from an electronic circuit of an electronic apparatus to light emitting elements 12, light is emitted from the plurality of light emitting elements 12. The light passes across touch panel 6 and illuminates a plurality of display portions 13B of display sheet 13 from below, and thereby, the display of letters, marks or the like of display portion 13B can be easily distinguished, and it is possible to easily perform the operation.
That is, the portion subjected to touch operation of display sheet 13 is detected by the electronic circuit in accordance with the capacitance change of touch panel 6. Further, each portion pressed is detected by the electronic circuit in accordance with electrical connection and disconnection of fixed contact 11. Also, light is emitted from a plurality of light emitting diodes 12 by the function of the electronic circuit. The conventional switch is configured in that a plurality of display portions 13B of display sheet 13 are illuminated through these operations.
However, in movable contact body 9 mentioned above and a switch using the contact, a plurality of light emitting elements 12 are disposed between a plurality of movable contacts 8, and light is emitted from light emitting elements 12 for illuminating a plurality of display portions 13B of display sheet 13. Accordingly, it is necessary to use many light emitting elements 12, requiring much time for the manufacture, and there arises a problem of costs.